A witness who qualifies as an expert because of knowledge, skill, experience, training, or education may testify as an expert if scientific, technical, or other specialized knowledge will assist the judge, jury, or other factfinder to understand the evidence or determine a contested fact issue.

But there is no rigid formula for determining whether a particular witness is qualified to testify as an expert. Generally there must be a fit between the subject matter at issue and the expert witness’s familiarity with the subject matter. And this determination is made by the judge, who acts as a gatekeeper to only allow reliable expert witness testimony to be heard and considered by the judge or jury.

In South Carolina, expert witness testimony is governed by rules that allow a witness with specialized knowledge, skill, experience, training, or education to provide testimony if it will help the court understand the evidence or resolve a disputed fact. The determination of whether a witness qualifies as an expert is not based on a strict formula but rather on the relevance and reliability of the witness's expertise in relation to the subject matter of the case. The judge serves as a gatekeeper, assessing the appropriateness of the expert's testimony, ensuring that it is not only pertinent to the case but also based on a reliable foundation. This gatekeeping role is crucial to prevent unreliable expert testimony from influencing the outcome of a trial. The judge's decision to admit expert testimony takes into account factors such as the expert's qualifications, the methodology used, and the applicability of the expert's knowledge to the facts of the case.